Preparation method of egg yolk microgel pickering emulsion with high emulsification stability

Abstract

The application discloses a preparation method of egg yolk microgel with oil-water two-phase and a stable emulsion preparation method thereof, and mainly comprises the following steps: obtaining an egg yolk gel solution by dispersing full-cooked egg yolk microgel or stirred egg yolk microgel at high speed, further processing the egg yolk gel solution by high-pressure homogenization to obtain an egg yolk microgel dispersion, and obtaining the egg yolk microgel by high-speed centrifugation and taking the bottom precipitate, then adding edible oil and processing by high-speed shearing to obtain a Pickering emulsion. The egg yolk microgel has high emulsification stability, the prepared Pickering emulsion is high in safety and good in stability, is still stable after being stored at 4 DEG C for more than 30 days, and can be applied to the fields of food, cosmetics and medicine.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of food processing, and in particular, relates to a preparation method of egg yolk microgel with oil-water dual phases and a stable emulsion preparation method. BACKGROUND

[0002] An emulsion system is a heterogeneous system formed by mixing two immiscible liquids. However, emulsions have thermodynamic instability characteristics, and often suffer from instability behaviors such as flocculation and oil droplet aggregation during processing, transportation and storage, thereby leading to phase separation of the system. In order to ensure the stability of the emulsion, an emulsifier is essential. Selecting a suitable emulsifier is one of the key factors for forming and stabilizing the emulsion. Although synthetic surfactants are often used in the preparation of emulsions due to their excellent emulsifying performance, the practical application of such synthetic small-molecule surfactants in the food industry is limited due to factors such as production cost, health problems, environmental protection, "clean label" requirements and legal restrictions. Therefore, it is extremely important to develop food-grade ingredients derived from nature, which are healthier and more environmentally friendly, as emulsifiers to replace synthetic surfactants.

[0003] Egg yolk is a natural material, and in the food industry, it is widely used as a natural emulsifier due to its significant emulsifying capacity of biological macromolecules such as proteins and lipids. However, due to its poor emulsifying stability, instability and separation often occur in high oil content products. At present, research on improving the emulsifying properties of egg yolk mainly focuses on maintaining the integrity of the yolk ball structure, and the performance of egg yolk is improved by physical or chemical treatment. However, for egg yolk that has been destroyed and transformed into a gel-like state, there is still a lack of effective methods to improve its emulsifying stability after the internal yolk ball structure changes. SUMMARY

[0004] In view of the deficiencies in the prior art, the purpose of the present application is to provide a preparation method of egg yolk microgel Pickering emulsion containing oil-water dual components and having high emulsifying stability, which overcomes the problem of denaturation of proteins and reduction of functional properties of traditional egg yolk gel after heat treatment.

[0005] In order to achieve the above technical purpose, the present inventors have not given up exploration through a large number of experimental researches, first, the egg yolk gel after heat crosslinking is physically treated, these treatments aim to optimize the structure of active ingredients such as proteins and lipids in egg yolk and enhance its hydrophilic-hydrophobic balance ability, thereby effectively improving the emulsifying effect, then the egg yolk after improved treatment is mixed with oil phase material of a specific ratio to form an emulsion system with high stability.

[0006] In particular, the object of the present application is achieved by a method for preparing an egg yolk microgel Pickering emulsion with high emulsion stability, comprising the following steps:

[0007] (1) dispersing the egg yolk gel obtained by preliminary breaking in a sodium chloride solution, and then stirring to obtain an egg yolk gel dispersion;

[0008] (2) dispersing the dispersion obtained in step (1) by high-speed dispersion machine at a speed of 7000-10000 r / min for 20-50 min;

[0009] (3) stirring the dispersion obtained in step (2) at a low speed of 500-1000 rpm at a temperature of 3-5°C for 6-8 h;

[0010] (4) filtering the dispersion obtained in step (3) through a 40-80 mesh screen;

[0011] (5) subjecting the filtrate obtained in step (4) to high-pressure homogenization at a pressure of 15-90 MPa, and then subjecting it to high-speed centrifugation at a speed of 8000-12000 r / min at a temperature of 3-5°C for 5-15 min, and the bottom precipitate is the egg yolk microgel particles;

[0012] (6) adding the dispersion of the egg yolk microgel particles obtained in step (5) as the water phase to the oil phase of edible oil, and the volume ratio of the water phase to the oil phase is 1:(1.1-1.3), and then subjecting it to high-speed shearing at a speed of 8000-12000 r / min for 0.5-2 min to obtain the egg yolk microgel Pickering emulsion.

[0013] Further preferably, the method for preparing an egg yolk microgel Pickering emulsion with high emulsion stability as described above, wherein the egg yolk gel in step (1) is a fully cooked egg yolk microgel or a stirred egg yolk microgel, and the fully cooked egg yolk microgel is obtained by cooking a chicken egg with shell until the egg yolk is separated, and the stirred egg yolk microgel is obtained by cooking the separated egg yolk liquid after stirring. The preferred method for cooking is in a water bath at 100°C.

[0014] Further preferably, the method for preparing an egg yolk microgel Pickering emulsion with high emulsion stability as described above, wherein the concentration of the sodium chloride solution in step (1) is 0.1-0.2 mol / L.

[0015] Further preferably, the method for preparing an egg yolk microgel Pickering emulsion with high emulsion stability as described above, wherein the mass ratio of the egg yolk gel to the sodium chloride solution in step (1) is 1:(8-12).

[0016] Further preferably, the method for preparing the egg yolk microgel Pickering emulsion with high emulsification stability as described above, the stirring condition in step (1) is 500-1000 rpm, 0.5-1 h.

[0017] Further preferably, the method for preparing the egg yolk microgel Pickering emulsion with high emulsification stability as described above, the speed of the high-speed disperser in step (2) is 8000-9000 r / min, and the processing time is 28-32 min.

[0018] Further preferably, the method for preparing the egg yolk microgel Pickering emulsion with high emulsification stability as described above, when the egg yolk gel is a fully cooked egg yolk microgel, the pressure of the high-pressure homogenization treatment in step (5) is preferably 60 MPa; when the egg yolk gel is a stirred egg yolk microgel, the pressure of the high-pressure homogenization treatment in step (5) is preferably 75-90 MPa.

[0019] Further preferably, the method for preparing the egg yolk microgel Pickering emulsion with high emulsification stability as described above, the parameters of the high-speed centrifugation in step (5) are 10000 r / pm, 4℃, 10 min.

[0020] Further preferably, the method for preparing the egg yolk microgel Pickering emulsion with high emulsification stability as described above, the edible oil in step (6) is selected from one or two or more of the following: soybean oil, peanut oil, corn germ oil.

[0021] Further preferably, the method for preparing the egg yolk microgel Pickering emulsion with high emulsification stability as described above, the concentration of the egg yolk microgel particles in the aqueous phase in step (6) is 0.08-0.12 g / ml.

[0022] Compared with the prior art, the present application has the following advantages and progress:

[0023] 1. The present application physically processes the egg yolk gel after thermal crosslinking, thereby optimizing the structure of active ingredients such as proteins and lipids inside the egg yolk and enhancing its hydrophilic-hydrophobic balance ability, successfully overcoming the problem of protein denaturation and reduced functional properties of traditional egg yolk gel after heat treatment.

[0024] 2. The present application uses high-pressure homogenization technology to physically modify the egg yolk gel, avoiding the use of any harmful reagents and chemical additives, and truly achieving green environmental protection. The egg yolk microgel particles treated by high-pressure homogenization exhibit higher emulsification stability and better functional properties.

[0025] 3、The present application can break into food-grade microgel particles by using existing food industry equipment, and further prepare environment-friendly natural Pickering emulsifiers. The method is a simple, economical and suitable for factory production of high-value and high-quality utilization method of egg yolk processing by-products, and widens the application range of egg yolk in food.

[0026] 4、The egg yolk microgel particles prepared by the present application have high emulsification stability, and the emulsion can be stored stably at 4℃ for 30 days; in addition, the unique oil-containing water dual-phase structure of the egg yolk microgel enables it to act as an emulsifier and effectively encapsulate active nutrients, providing a new solution for the delivery of nutrients. BRIEF DESCRIPTION OF DRAWINGS

[0027] Figure 1 Figure 4 is a particle size distribution diagram of egg yolk microgel.

[0028] Figure 2 Figure 6 is the emulsification activity and emulsification stability of egg yolk microgel.

[0029] Figure 3 Figure 8 is a confocal image of emulsion droplets stabilized by fully cooked egg yolk microgel.

[0030] Figure 4 Figure 10 is a confocal image of emulsion droplets stabilized by stirred egg yolk microgel.

[0031] Figure 5 Figure 12 is a macrograph of fully cooked egg yolk microgel-stabilized emulsion at different storage times.

[0032] Figure 6 Figure 14 is a macrograph of stirred egg yolk microgel-stabilized emulsion at different storage times. DETAILED DESCRIPTION

[0033] The present application will be further described below in conjunction with the embodiments and drawings, and the advantages and characteristics of the present application will be more apparent with the description of the embodiments. However, it should be understood that the described embodiments are only exemplary and do not constitute any limitation on the protection scope of the present application. Those skilled in the art should also understand that modifications or substitutions can be made to the details and forms of the technical solutions without departing from the spirit of the present application, and such modifications or substitutions all fall within the protection scope of the present application. In addition, the experimental methods in the following embodiments are conventional methods in the art unless otherwise specified. Moreover, the test methods of some technical indicators in the following embodiments are as follows:

[0034] (1) Egg yolk microgel and emulsion droplet particle size distribution test: dilute the microgel and emulsion by an appropriate multiple to avoid the influence of multiple scattering. Then, a microlaser particle size instrument (Malvern Instruments Ltd., Worcestershire, UK) is used to determine the particle size of the emulsion.

[0035] (2) Emulsifying property determination method: 20 μL of emulsion was mixed with 8 mL of sodium dodecyl sulfate (SDS) buffer (i.e. 0.1%, w / v). After vortex mixing for 5 s, the absorbance (A0) of the freshly prepared emulsion sample was immediately measured at 500 nm using a UV spectrophotometer (UV1901PC, Shanghai Aoxiang Scientific Instrument Co., Ltd., Shanghai, China), and the absorbance (A30) was measured again after 30 min. 30 ) Emulsifying activity (EAI) and emulsion stability (ESI) were calculated using the following formulas

[0036] The calculation formula is as follows:

[0037]

[0038]

[0039] In the formula:

[0040] N - dilution factor (401)

[0041] C - dry matter concentration of egg yolk microgel solution before emulsification (0.1 g / mL)

[0042] F - volume fraction of oil in emulsion (55%)

[0043] Δt - interval time 30 min

[0044] A0 - absorbance at 0 min

[0045] A 30 - absorbance at 30 min

[0046] Example 1

[0047] A method for preparing an egg yolk microgel with oil-water biphase and a stable emulsion preparation method thereof, comprising the following steps:

[0048] (1) Shell eggs were boiled at 100°C for 30 min, and the intact egg yolk gel was preliminarily broken by a meat grinder. Then the broken whole boiled egg yolk gel was added into 0.15 mol / L sodium chloride solution at a ratio of 1:10 and stirred. After uniform stirring (500 rpm, 0.5 h), the high-speed disperser was used to break the whole boiled egg yolk gel dispersion at 8000 r / min for 30 min. The obtained whole boiled egg yolk gel dispersion was placed in a 4°C condition and stirred at 800 rpm for 7 h on a stirrer.

[0049] (2) The whole-cooked egg yolk gel dispersion obtained in step (1) was filtered through a 60-mesh sieve, and then treated by a high-pressure homogenizer at 15 MPa for one cycle to obtain a whole-cooked egg yolk microgel solution.

[0050] (3) The whole-cooked egg yolk microgel solution was subjected to high-speed centrifugation (10000 r / pm, 4℃, 10 min) to obtain whole-cooked egg yolk microgel particles.

[0051] (4) 55% soybean oil and 45% whole-cooked egg yolk microgel particle dispersion (0.1 g / ml) were weighed by volume ratio and mixed uniformly, and then placed in a high-speed disperser with a rotation speed of 10000 r / min for whipping for 1 min to obtain a base emulsion.

[0052] Example 2

[0053] A method for preparing a whole-cooked egg yolk microgel with oil-water biphase and a stable emulsion thereof. Compared with the steps of Example 1, only the high-pressure homogenization condition of the high-pressure homogenizer in step (2) was changed to 30 MPa. The other steps were the same as Example 1.

[0054] Example 3

[0055] A method for preparing a whole-cooked egg yolk microgel with oil-water biphase and a stable emulsion thereof. Compared with the steps of Example 1, only the high-pressure homogenization condition of the high-pressure homogenizer in step (2) was changed to 45 MPa. The other steps were the same as Example 1.

[0056] Example 4

[0057] A method for preparing a whole-cooked egg yolk microgel with oil-water biphase and a stable emulsion thereof. Compared with the steps of Example 1, only the high-pressure homogenization condition of the high-pressure homogenizer in step (2) was changed to 60 MPa. The other steps were the same as Example 1.

[0058] Example 5

[0059] A method for preparing a whole-cooked egg yolk microgel with oil-water biphase and a stable emulsion thereof. Compared with the steps of Example 1, only the high-pressure homogenization condition of the high-pressure homogenizer in step (2) was changed to 75 MPa. The other steps were the same as Example 1.

[0060] Example 6

[0061] A method for preparing a whole-cooked egg yolk microgel with oil-water biphase and a stable emulsion thereof. Compared with the steps of Example 1, only the high-pressure homogenization condition of the high-pressure homogenizer in step (2) was changed to 90 MPa. The other steps were the same as Example 1.

[0062] Comparative Example 1

[0063] A preparation method of yolk microgel with oil-water biphase and a preparation method of stable emulsion thereof. Relative to the steps of Example 1, only the high-pressure homogenization condition of the high-pressure homogenizer in step (2) is changed to 0 MPa. The other steps are the same as those in Example 1.

[0064] Example 7

[0065] A preparation method of yolk microgel with oil-water biphase and a preparation method of stable emulsion thereof, comprising the following steps:

[0066] (1) A whole egg is broken, and the yolk is separated out. The yolk membrane is pierced with a pair of tweezers to obtain yolk liquid. The obtained yolk liquid is collected in a beaker and placed on a stirrer for stirring for 30 min. Then the stirred yolk liquid is sealed with plastic wrap and placed in boiling water at 100°C for boiling for 30 min to obtain a stirred yolk gel. The stirred yolk gel is broken by a meat grinder, and then the broken stirred yolk gel is added into a sodium chloride solution (0.15 mol / L) at a ratio of 1:10 and stirred. After being stirred uniformly (500 rpm, 0.5 h), the stirred yolk gel dispersion obtained by high-speed dispersion at 8000 r / min for 30 min is placed on a stirrer and stirred at 800 rpm for 7 h.

[0067] (2) The stirred yolk gel dispersion obtained in step (1) is filtered once through a 60-mesh sieve, and then treated by a high-pressure homogenizer at 15 MPa for one cycle to obtain a stirred yolk microgel solution.

[0068] (3) The stirred yolk microgel solution is subjected to high-speed centrifugation (10000 r / min, 4°C, 10 min) to obtain stirred yolk microgel particles.

[0069] (4) 55% soybean oil and 45% stirred yolk microgel particle dispersion (0.1 g / ml) are weighed according to the volume ratio and uniformly mixed, and then placed in a high-speed dispersion machine at a speed of 10000 r / min for whipping for 1 min to obtain a basic emulsion.

[0070] Example 8

[0071] A preparation method of yolk microgel with oil-water biphase and a preparation method of stable emulsion thereof. Relative to the steps of Example 7, only the high-pressure homogenization condition of the high-pressure homogenizer in step (2) is changed to 30 MPa. The other steps are the same as those in Example 7.

[0072] Example 9

[0073] A preparation method of yolk microgel with oil-water biphase and a preparation method of stable emulsion thereof. Relative to the steps of Example 7, only the high-pressure homogenization condition of the high-pressure homogenizer in step (2) is changed to 45 MPa. The other steps are the same as those in Example 7.

[0074] Example 10

[0075] A preparation method of yolk microgel with oil-water biphase and a preparation method of stable emulsion thereof. Relative to the steps of Example 7, only the high-pressure homogenization condition of the high-pressure homogenizer in step (2) is changed to 60 MPa. Other steps are the same as Example 7.

[0076] Example 11

[0077] A preparation method of yolk microgel with oil-water biphase and a preparation method of stable emulsion thereof. Relative to the steps of Example 7, only the high-pressure homogenization condition of the high-pressure homogenizer in step (2) is changed to 75 MPa. Other steps are the same as Example 7.

[0078] Example 12

[0079] A preparation method of yolk microgel with oil-water biphase and a preparation method of stable emulsion thereof. Relative to the steps of Example 7, only the high-pressure homogenization condition of the high-pressure homogenizer in step (2) is changed to 90 MPa. Other steps are the same as Example 7.

[0080] Comparative Example 2

[0081] A preparation method of yolk microgel with oil-water biphase and a preparation method of stable emulsion thereof. Relative to the steps of Example 7, only the high-pressure homogenization condition of the high-pressure homogenizer in step (2) is changed to 0 MPa. Other steps are the same as Example 7.

[0082] The yolk microgel particles and yolk microgel emulsions obtained in each example were subjected to performance tests, and the test results are as follows:

[0083] Figure 1 The particle size distribution diagram of the yolk microgel prepared in Examples 1-12 and Comparative Examples 1-2. From the particle size distribution diagram, it can be seen that the particle size of the yolk microgel gradually decreases from Comparative Example 1 to Comparative Example 2 and Example 1 to Example 12. Figure 1 It can be seen that: compared with Comparative Examples 1 and 2, the size of the yolk microgel of the examples gradually decreases, and the particle size obtained in Examples 6 and 12 is the smallest and the dispersion is more uniform.

[0084] Figure 2 The emulsification activity and emulsion stability statistical diagram of the yolk microgel prepared in each example. From the statistical diagram, it can be seen that the emulsification activity and emulsion stability of the yolk microgel gradually increase from Comparative Example 1 to Comparative Example 2 and Example 1 to Example 12. Figure 2It can be seen that the emulsification activity of Comparative Example 1 is the lowest; the emulsification activity and emulsification stability of the fully-cooked egg yolk microgel gradually increase and then decrease with the increase of the high-pressure homogenization pressure, and the emulsification activity of Example 4 reaches the highest value; the emulsification activity and emulsification stability of the stirred egg yolk microgel gradually increase with the increase of the high-pressure homogenization pressure, and reach the maximum at the highest pressure value; the emulsification activity of Comparative Example 2 and Examples 7-12 is higher than that of Comparative Example 1 and Examples 1-6, which indicates that the moderate high-pressure treatment of the fully-cooked egg yolk microgel and the higher pressure treatment of the stirred egg yolk microgel have a good promoting effect on the emulsification of the egg yolk microgel, and the emulsification activity of the stirred egg yolk microgel is obviously higher than that of the fully-cooked egg yolk microgel.

[0085] Figure 3 、 4 The confocal images of the emulsion droplets show that the emulsion droplet size of Comparative Examples 1 and 2 is large and unevenly distributed, the internal emulsion droplet size of Examples 2, 3, 4, 11 and 12 is small and more orderly arranged, and the distribution is more uniform. It indicates that the emulsification of the egg yolk microgel treated by high-pressure homogenization is improved, which is more conducive to the formation of small-size and uniformly distributed emulsion droplets.

[0086] Figure 5 The storage stability statistical chart and physical chart of the emulsions prepared in Examples 1-6 and Comparative Example 1 after being placed at 4℃ for 30 days are shown in FIG. 2 and FIG. 3, respectively. Figure 5 It can be seen that the emulsions prepared by different high-pressure homogenization pressures show different storage stabilities. The stability of Comparative Example 1 is poor, and obvious demulsification phenomenon occurs; compared with Comparative Example 1, Examples 1, 2, 3, 5 and 6 show improved storage stability; the emulsion obtained in Example 4 does not show obvious layering phenomenon after being stored for 30 days, and shows the best storage stability, which indicates that it can be stored stably at 4℃ for 30 days without the phenomenon of emulsion layering.

[0087] Figure 6 The storage stability statistical chart and physical chart of the emulsions prepared in Examples 7-12 and Comparative Example 2 after being placed at 4℃ for 30 days are shown in FIG. 4 and FIG. 5, respectively. Figure 6 It can be seen that the emulsification activity of the stirred egg yolk microgel is consistent with the change trend of the emulsification activity, and with the increase of the pressure, the emulsion creaming index decreases, and the emulsion storage stability gradually increases, and Example 12 has better storage stability. Combined with Figure 5 and Figure 6 it is found that the storage stability of the emulsion prepared by the stirred egg yolk microgel is better than that of the fully-cooked egg yolk microgel.

Claims

1. A method for preparing an egg yolk microgel Pickering emulsion with high emulsification stability, characterized in that, The method includes the following steps: (1) The egg yolk gel is initially broken and dispersed in a sodium chloride solution, and then stirred to obtain an egg yolk gel dispersion; the concentration of the sodium chloride solution is 0.1-0.2 mol / L; the mass ratio of the egg yolk gel to the sodium chloride solution is 1:(8-12). (2) The dispersion obtained in step (1) is dispersed and crushed at a high speed of 7000-10000 r / min for 20-50 min using a high-speed disperser; (3) The dispersion obtained in step (2) is stirred at low speed at 3-5℃ for 6-8 hours at a stirring speed of 500-1000 rpm. (4) Filter the dispersion obtained in step (3) through a 40-80 mesh sieve; (5) The filtrate obtained in step (4) is subjected to high pressure homogenization at a pressure of 15-90 MPa, and then centrifuged at 3-5℃ at a speed of 8000-12000 rpm for 5-15 min. The bottom precipitate is egg yolk microgel particles. (6) The dispersion of egg yolk microgel particles obtained in step (5) is added to the oil phase of edible oil as the aqueous phase. The volume ratio of the aqueous phase to the oil phase is 1: (1.1-1.3). Then, high-speed shearing is performed at a shearing speed of 8000-12000 r / min and a shearing time of 0.5-2 min to obtain egg yolk microgel Pickering emulsion.

2. The method for preparing the egg yolk microgel Pickering emulsion with high emulsification stability according to claim 1, characterized in that, The egg yolk gel mentioned in step (1) is either a fully boiled egg yolk microgel or a stirred egg yolk microgel. The fully boiled egg yolk microgel is obtained by boiling an egg in its shell and separating the yolk, while the stirred egg yolk microgel is obtained by boiling the separated egg yolk liquid after stirring.

3. The method for preparing the egg yolk microgel Pickering emulsion with high emulsification stability according to claim 1, characterized in that, The stirring conditions in step (1) are 500-1000 rpm and 0.5-1 h.

4. The method for preparing the egg yolk microgel Pickering emulsion with high emulsification stability according to claim 1, characterized in that, In step (2), the speed of the high-speed disperser is 8000-9000 r / min, and the processing time is 28-32 min.

5. The method for preparing the egg yolk microgel Pickering emulsion with high emulsification stability according to claim 2, characterized in that, When the egg yolk gel is a fully cooked egg yolk microgel, the pressure of the high-pressure homogenization process in step (5) is 60 MPa; when the egg yolk gel is a stirred egg yolk microgel, the pressure of the high-pressure homogenization process in step (5) is 75-90 MPa.

6. The method for preparing the egg yolk microgel Pickering emulsion with high emulsification stability according to claim 1, characterized in that, The parameters for high-speed centrifugation in step (5) are 10,000 rpm, 4°C, and 10 min.

7. The method for preparing the egg yolk microgel Pickering emulsion with high emulsification stability according to claim 1, characterized in that, The edible oil mentioned in step (6) is selected from one or more of the following: soybean oil, peanut oil, and corn germ oil.

8. The method for preparing the egg yolk microgel Pickering emulsion with high emulsification stability according to claim 1, characterized in that, The concentration of egg yolk microgel particles in the aqueous phase in step (6) is 0.08-0.12 g / ml.

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